This invention relates to processes for making antimicrobial compounds. The compounds made by this invention contain, as integral substituents, a quinolone moiety and a lactam-containing moiety.
The chemical and medical literature describes a myriad of compounds that are said to be antimicrobial, i.e., capable of destroying or suppressing the growth or reproduction of microorganisms, such as bacteria. In particular, antibacterials include a large variety of naturally-occurring (antibiotic), synthetic, or semi-synthetic compounds. They may be classified (for example) as the aminoglycosides, ansamacrolides, beta-lactams (including penicillins and cephalosporins), lincosaminides, macrolides, nitrofurans, nucleosides, oligosaccharides, peptides and polypeptides, phenazines, polyenes, polyethers, quinolones, tetracyclines, and sulfonamides. Such antibacterials and other antimicrobials are described in Antibiotics, Chemotherapeutics, and Antibacterial Agents for Disease Control (M. Grayson, editor, 1982), and E. Gale et al., The Molecular Basis of Antibiotic Action 2d edition (1981), both incorporated by reference herein.
Recently, a new class of highly potent, broad spectrum antimicrobials was discovered, combining beta-lactam moieties with quinolone moieties. These compounds have been referred to as "Quinolonyl Lactam Antimicrobials" (herein referred to as "QLAs)." Such compounds are described in European Patent Publication 366,189, White and Demuth, published May 2, 1990; European Patent Publication 366,193, Demuth and White, published May 2, 1990; European Patent Publication 366,640, Demuth and White, published May 2, 1990; and European Patent Publication 366, 641, White and Demuth, published May 2, 1990. Other such compounds are described in Australian Patent Publication 87/75009, Albrecht et al., published Jan. 7, 1988; Australian Patent Publication 88/27554, published Jun. 6, 1989; European Patent Publication 335, 297, Albrecht et al., published Oct. 4, 1989; and Albrecht et al., "Dual-Action Cephalosporing: Cephalosporin 3'-Quinolone Carbamates", 34 J. Medicinal Chemistry 2857 (1991).
Manufacture of QLAs generally involves synthesis of suitably protected substituent beta-lactam and quinolone moieties, a linking process, and appropriate de-protection steps. The specific linking process depends, of course, on the specific lactam and quinolone substituent moieties used, as well as the type of linkage desired. Several such linking processes have been described in the literature. However, the yields of these processes are often low, particularly for the preparation of QLAs having a penem substituent moiety.
It has now been discovered that certain linking processes using phosgene are useful in making QLAS, particularly those having a penem substituent moiety. Such processes allow efficient synthesis of QLAS, with high yields.